Asus ESC2000 Personal SuperComputer - Manual (Page 70)

Chapter 4: Motherboard information 4-16
10. Serial port connector (10-1 pin COM2)
This connector is for a serial (COM) port. Connect the serial port module
cable to this connector, then install the module to a slot opening at the back
of the system chassis.
11. BMC header (BMC_FW1)
The BMC connector on the motherboard supports an ASUS ® Server
Management Board 4 Series (ASMB4).